Automatic machinery is used in modern bottling facilities for filling containers with gaseous liquid containing carbon dioxide and similar carbonation under counter pressure, and for filling containers with nongaseous liquids. The machinery enables predetermined quantities of liquid to be delivered into the containers. The machinery includes mechanisms for handling the containers in which the empty containers are raised until the neck engages the filling device in order to receive a predetermined volume of liquid at which time the containers are lowered and directed toward the machine. The filling machinery includes a reservoir containing a liquid which flows under the effective gravity. The gas above the liquid maintains the carbon dioxide in the liquid and is used to charge the container. A filling valve is located in the reservoir and extends through the tank. The filling valve connects the reservoir with the empty container and opens to allow the container to be filled with liquid. When the container is engaged with the filling device, the gas valve fills the container with counter pressure gas. The bottle is then filled with liquid by opening the filling valve. During filling, the gas contained in the container is evacuated through a vent tube toward a gas chamber in the tank. As soon as the level of liquid in the container reaches the aperture of the tube, the gas, which is located in the neck of the container, can no longer escape and the flow is stopped. The liquid and gas valves are then closed. A snifter is operated to release the remaining pressure in the container and in the valve stem.
U.S. Pat. No. 4,979,546, issued Dec. 25, 1990 in the name of LaWarre, Sr. et al, and assigned to the assignee of the subject invention, discloses a filling valve assembly operative to fill containers to predetermined heights. The apparatus utilizes a vent tube extending through the housing from the charging cap which is directly actuated upon by the actuator or lever. The problem with this type of assembly is that the entire gas contained within the vent tube must be snifted. The proportion of gas to liquid in smaller containers increases which causes a great amount of foaming during the snifting process. Therefore, it is desirable to decrease the amount of gas in the vent tube snifted.
U.S. Pat. Nos. 4,140,158 to Heckmann et al and U.S. Pat. No. 3,757,835, issued to Copping and U.S. Pat. No. 3,699,740, issued to Knabe discloses filling valve systems which have a shortened vent tube. However, vent tube is shortened by utilizing a restriction within the original vent tube in order to adjust the valve tube length in the post valve. This design designs back pressure in the post valve area, slows the counter pressure, and slows escapement of CO.sub.2.